Risk factors for Eimeria infections are well documented in farm and pet animals, but studies focusing on wildlife species are less common. This research aimed to investigate the impact of selected demographic and environmental factors on the prevalence of Eimeria in the European hare (Lepus europaeus). Additionally, we analysed whether Eimeria infection affected the behaviour of hares by examining the relationship between infection status and the likelihood of a hare being killed by a vehicle at a hotspot for road mortality. Between 11 February 2022 and 24 June 2024, we collected 22 hare carcasses that had been killed in traffic along an 83.9 km monitoring route in central Bohemia, Czech Republic, to evaluate Eimeria prevalence in relation to factors such as age, hare density, distance to the nearest water source and rainfall over the previous 3 months. Contrary to our expectations, we found a higher prevalence of Eimeria in adult hares compared to juveniles. We propose that this outcome may be due to the high mortality rates among leverets and juvenile hares, which removes susceptible individuals from the population early on. The effects of the other factors examined were not significant. In conclusion, our study revealed that Eimeria infection did not contribute to the clustering of hare–vehicle collisions. We emphasize the importance of studying risk factors in wildlife species across different ecological contexts. Our findings challenge the general assumption that age negatively influences Eimeria prevalence.

Laetisaria macrospora is a new species of lichenicolous Corticiaceae forming light pink to coral coloured basidiomata on Physcia adscendens and P. stellaris. The basidiomata are usually located on the lower surface of the host thallus and produce basidia with four sterigmata and relatively large basidiospores, 23–34 × 11–18 μm. Phylogenetic analyses using nuITS sequences fully support the placement of the new species in Laetisaria, a genus that is recovered as monophyletic. Laetisaria macrospora was discovered in the Massif Central (France) in lichen communities growing on branches of Juniperus and Genista at the summit of the Puy de Manson.

Exposure to environmentally transmitted parasites should increase with population density due to accumulation of infective parasites in space. However, resource competition also increases with density, lowering immunity and increasing susceptibility, offering an alternative pathway for density-dependent infection. To test the relationships between these two processes and parasitism, we examined associations between host density, resource availability, immunity, and counts of 3 common helminth parasites using a long-term study of red deer. We found evidence that immunity increased with resource availability while parasite counts declined with immunity. We also found that greater density correlated with reduced resource availability, and while density was positively associated with both strongyle and tissue worm burdens, resource availability was independently and negatively associated with the same burdens. Our results support separate roles of density-dependent exposure and susceptibility in driving infection, providing evidence that resource competition is an important driver of infection, exacerbating effects of density-dependent increases in exposure.

Detection approaches based on environmental DNA (eDNA) are widely used for free-living species but remain underutilized for parasite species. This study applies eDNA detection methods to elucidate the life cycle of the trematode Curtuteria arguinae, which infects the socioeconomically and ecologically important edible cockle (Cerastoderma edule) as its second intermediate host along the northeastern Atlantic coast, including Arcachon Bay, France. The first intermediate and definitive hosts remained unknown. To identify these hosts – presumed to be a gastropod and a shorebird – we developed a quantitative PCR (qPCR)-based eDNA approach targeting partial cox1 and SSU gene regions of C. arguinae. We tested for C. arguinae eDNA presence in water samples containing separately five dominant gastropod species and fecal samples from known cockle predators, the European oystercatcher (Haematopus ostralegus) and gulls (Larus spp.), collected in Arcachon Bay. C. arguinae eDNA was only detected in water containing the needle snail (Bittium reticulatum), with cercarial emergence confirming infection in 1.6% of individual hosts. Morphological analysis of the cercarial and metacercarial stages revealed variability in collar spine visibility. Additionally, C. arguinae was detected by qPCR in 42% of oystercatcher feces and no gull feces, suggesting oystercatchers are the definitive host. This study is the first to elucidate the complete life cycle of C. arguinae, identifying B. reticulatum as its first intermediate host and H. ostralegus as its definitive host. Our findings highlight the potential of eDNA approaches for resolving parasite life cycles and enabling advances in ecological research on C. arguinae.

Many marine invertebrates are intermediate hosts to parasites. As some of these parasites may influence host behaviour and act as cryptic agents involved in mass mortality, knowledge of their presence, dynamics, and life cycles is important. Our aim with the present study is to provide a survey of parasites in subtidal cockles in the Limfjorden (Denmark), to examine their influence on cockles, and to assess their possible role in the surfacing of cockles, as this phenomenon is considered a prelude to mortality. The trematode fauna of the studied subtidal population was poor in species, but about 19% of the examined cockles in late summer and autumn were infected by Monorchis parvus – a species not previously reported from cockles in Danish waters. Heavily infected cockles were filled with small, undulating, worm-like sporocysts, each filled with metacercariae. From August to November, the number of metacercariae in sporocysts increased, and at a certain point, the growing stock of sporocysts is supposed to reach a level where the cockle is unable to perform vital life functions. Our data show that infected individuals exhibit less annual shell growth than uninfected ones. There was no significant difference in the prevalence of M. parvus between unburied and buried cockles. Cockle-eating fish from the family Sparidae are known as final hosts to M. parvus, but these fish do not occur in Danish waters. Therefore, the record-high presence of M. parvus in cockles from the Limfjorden is surprising, and we consider alternative life cycle options for this trematode.

Human toxocariasis is a worldwide parasitic disease caused by zoonotic roundworms of the genus Toxocara, which can cause blindness and epilepsy. The aim of this study was to estimate the risk of food-borne transmission of Toxocara spp. to humans in the UK by developing mathematical models created in a Bayesian framework. Parameter estimation was based on published experimental studies and field data from southern England, with qPCR Cq values used as a measure of eggs in spinach portions and ELISA optical density data as an indirect measure of larvae in meat portions. The average human risk of Toxocara spp. infection, per portion consumed, was estimated as 0.016% (95% CI: 0.000–0.100%) for unwashed leafy vegetables and 0.172% (95% CI: 0.000–0.400%) for undercooked meat. The average proportion of meat portions estimated positive for Toxocara spp. larvae was 0.841% (95% CI: 0.300–1.400%), compared to 0.036% (95% CI: 0.000–0.200%) of spinach portions containing larvated Toxocara spp. eggs. Overall, the models estimated a low risk of infection with Toxocara spp. by consuming these foods. However, given the potentially severe human health consequences of toxocariasis, intervention strategies to reduce environmental contamination with Toxocara spp. eggs and correct food preparation are advised.

The Hippoboscidae are ectoparasites of birds and mammals, which, as a group, are known to vector multiple diseases. Avipoxvirus (APV) is mechanically vectored by various arthropods and causes seasonal disease in wild birds in the United Kingdom (UK). Signs of APV and the presence of louse flies (Hippoboscidae) on Dunnocks Prunella modularis were recorded over a 16·5-year period in a rural garden in Somerset, UK. Louse flies collected from this site and other sites in England were tested for the presence of APV DNA and RNA sequences. Louse flies on Dunnocks were seen to peak seasonally three weeks prior to the peak of APV lesions, an interval consistent with the previously estimated incubation period of APV in Dunnocks. APV DNA was detected on 13/25 louse flies, Ornithomya avicularia and Ornithomya fringillina, taken from Dunnocks, both with and without lesions consistent with APV, at multiple sites in England. Collectively these data support the premise that louse flies may vector APV. The detection of APV in louse flies, from apparently healthy birds, and from sites where disease has not been observed in any host species, suggests that the Hippoboscidae could provide a non-invasive and relatively cheap method of monitoring avian diseases. This could provide advanced warnings of disease, including zoonoses, before they become clinically apparent.

The parasites of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) are poorly documented in the United States despite the economic importance and global introduction of this African fish. Only one metazoan parasite (Gyrodactylus cichlidarum Paperna, 1968; Gyrodactylidae) reportedly infects Nile tilapia in the United States. Examining Nile tilapia from a flow-through aquaculture system hydrologically linked to Sougahatchee Creek (Tallapoosa River, Auburn, Alabama), we observed a gill infection by Cichlidogyrus sclerosus Paperna & Thurston, 1969 (Dactylogyridae). This monogenoid was originally described from the gill of Mozambique tilapia, Oreochromis mossambicus (Peters, 1852) from Lake Victoria, Uganda. Specimens of C. sclerosus were studied for morphology and phylogenetic analyses using the 28S and ITS1. We identified our specimens as C. sclerosus because they had the following combination of morphological features: marginal hooks shorter than dorsal anchor length; anchor roots reduced; dorsal anchor point bent; dorsal bar pyriform projections approximately half as long as dorsal bar width; penis short (<100 μm), not coiled, tubular, lacking swelling, having irregularly surfaced heel; and accessory piece straight and bifid. Our 28S and ITS1 phylogenies recovered our C. sclerosus sequences in a clade with conspecific sequences and showed no obvious biogeographic pattern. Cichlidogyrus sclerosus reportedly infects 21 fishes of 11 genera and 3 families from 36 countries in Africa, Asia, North America, South America, and Europe. The study of Nile tilapia parasites, especially those exhibiting direct life cycles and low host specificity, is important because they comprise potential invasive species.

The digenetic trematode Proctoeces maculatus is a cosmopolitan parasite that infects various invertebrates and fish hosts, including the blue mussel, Mytilus edulis, along the northeastern U.S. coast. Despite its impact on mussel fitness and the region’s aquaculture, little is known about the genetic diversity and connectivity of P. maculatus in this region. This study provides the first genetic characterization of P. maculatus populations in New England using the D1–D3 region of the 28S ribosomal RNA gene. Bayesian phylogenetic analysis and a haplotype network were used to assess genetic variation and connectivity across six localities in Maine, New York, and southern New England, and to compare these populations to global samples. Our results revealed distinct geographic structuring of P. maculatus haplotypes. The ME1 haplotype, unique to Maine, reflects either recent range expansion or isolation driven by environmental and biogeographic factors, such as Cape Cod’s role as a phylogeographic barrier. The most common haplotype, US1, was shared by populations in southern New England, New York, and a single specimen from Tunisia, indicating possible historical or anthropogenic connectivity. Two divergent haplotypes from Mississippi and Chile likely represent misidentifications or cryptic species. These findings support the hypothesis that P. maculatus is likely a cryptic species complex. Molecular evidence suggests connectivity across distant regions, emphasizing the role of host movement in parasite dispersal. Continued genetic studies, particularly from under-sampled regions, are needed to unravel the diversity and biogeography of P. maculatus and its potential impact on declining mussel populations.

Toxocara canis is a widespread parasite of canids with a wide range of paratenic hosts, but also one of the overlooked agents causing nervous system infections of humans. Previous experimental infections of mice demonstrated the impact of high infection doses of larvae on neurobehavioral disorders and pathological changes. In contrast to previous studies, we aimed to investigate the long-term (up to 100 weeks) impact of low- to high-dose infection in mice. We focused on their physical condition, motor skills, and the accompanying pathologies in the brain. Three groups of BALB/c mice were infected with 10, 100, and 1000 T. canis larvae/mouse and specific anti-T. canis excretory-secretory antigens immunoglobulin G antibody response, general condition, and motor skills were tested in defined intervals within 100 weeks after infection. The number of larvae in selected organs was assessed and the pathological changes in the brain were studied histologically. As a result, subtle to severe impairments in general condition and motor skills were detected, with generally earlier onsets occurring the higher the infection dose was. The specific immunoglobulin G antibody levels corresponding to the infection dose were detected in all infected groups. Necrosis, cellular infiltrations, and foamy cells developed in moderate- and high-infection dose mice, in contrast with hemorrhages detected in all groups. This study demonstrated the long-term negative impact of T. canis infection on the paratenic host, particularly at moderate and high infectious doses. Although pathological changes in the brain were observed even in low-infection dose mice, their physical and motor condition was comparable to the control group.

Austropotamobius pallipes complex is an endangered freshwater crayfish species in Europe and the assessment of the health status of its wild populations is essential for conservation purposes. The two microsporidia Astathelohania contejeani and Nosema austropotamobii have been reported to cause in A. pallipes complex a chronic parasitic infection, known as ‘porcelain disease’, which reduces population fitness and leads the host to death. Due to the similar macroscopic signs produced, molecular biology analyses are required to unambiguously distinguish between these microsporidia. Focusing on A. pallipes complex populations located in Northern and Central Italy, the present study provides an evaluation of prevalence and distribution of A. contejeani and N. austropotamobii, and investigates the variables affecting the probability of detecting infected specimens during a survey (e.g. sex, crayfish density, longitude). Microsporidia were identified in 12 populations among the 42 monitored from 2011 to 2017, with an average prevalence of 3.12% for A. contejeani and 3.60% for N. austropotamobii, the latter being reported in a wider area than previously documented (from Lombardy to Liguria Regions). Notably, crayfish co-infected by both microsporidia were also detected in 4 populations. Moreover, it was observed that the probability of detecting a crayfish with a microsporidian infection significantly increased eastwards in the studied area, especially for N. austropotamobii. Our distribution map for microsporidiosis, combined with molecular screening, will be useful for planning breeding and translocation efforts for A. pallipes complex populations.

Ascaridoidea (Nematoda) is a widespread superfamily of nematodes that comprises gastrointestinal parasites from all major groups of vertebrates. Although this taxon probably emerged in the Carboniferous, its Brazilian fossil record includes mostly eggs, found in ancient remains, collected in paleontological and archeological sites from the Mesozoic and Cenozoic Eras. The Tremembé Formation (Oligocene of the Taubaté Basin) has become an important source for paleoparasitological studies in avian coprolites during the third decade of the 21st century, with reports of eggs only at only a single cell stage, of embryonic development. Here we present the first egg of Ascaridoidea preserved containing morula, from a bird coprolite recovered from the shales of the Tremembé Formation. Three coprolites, from the outcrop of Aligra Comércio de Argila S/A, Taubaté municipality (State of São Paulo), were rehydrated and subjected to spontaneous sedimentation. Based on morphological and morphometric features and diet and zoopaleontological context, the trace fossils were assigned to piscivorous birds. The egg found showed morphological characteristics typical of Ascaridoidea: namely spherical form, ornamented, and somewhat thick shell. Moreover, this superfamily includes several taxa that infect piscivorous birds and fish in heteroxenous life cycles and produce eggs with similar features as the egg found in the present study. The paleoparasitological information associated with the paleofaunistic diversity of birds and fish from the Tremembé Formation, reveal that the ancient Brazilian paleoenvironments provided subsidies for the rise and success of nematodes infecting these animals during the Paleogene.

Although 12 soft tick species (Argasidae) are native to Australia, the ecology of most is poorly known. Argas dewae parasitizes several insectivorous bat species and has been recorded on humans. Therefore, understanding its ecology is crucial for wildlife health management and public health preparedness. To address this knowledge gap, A. dewae populations were monitored from 2 bat hosts (Chalinolobus gouldii and Austronomus australis) using bat boxes at 3 sites in Victoria, Australia, for 28 months (July 2005–December 2007). A phenological profile undertaken for A. dewae revealed that tick load on bat hosts increased throughout winter and peaked in the first month of spring, before collapsing and remaining low throughout the drier late spring and summer periods. There was also further investigation of the relationship between 2 response variables (tick infestation risk and tick load) and a range of explanatory variables (body condition index, sex, age class, bioseason, site, bat density per nest box). In C. gouldii, site was the only significant predictor of A. dewae infestation risk, while load was correlated with several variables including age class, sex, bioseason, roost density and body condition index. This paper also reports the first records of A. dewae from 6 bat species in 3 bat families (Miniopteridae: Miniopterus australis; Molossidae: A. australis; Vespertilionidae: Chalinolobus morio, Myotis Macropus, Vespadelus darlingtonia, Vespadelus regulus) and a second record of A. dewae from a human. The first distribution records are presented for A. dewae in South Australia, the Australian Capital Territory and Queensland.

A new species of Myxobolidae, Henneguya cardii n. sp., is described infecting the European seabass Dicentrarchus labrax, a fish of high commercial value intensively cultivated in southern Europe. Henneguya cardii n. sp. was found in the bulbus arteriosus and spleen with a prevalence of infection of 13.5%. In the heart, it forms irregular whitish plasmodia measuring 1 mm in size. Mature myxospores are broadly obovoid in frontal view and ellipsoidal in lateral view, with 2 equal caudal appendages. Polar capsules are ovoid and symmetric, with 3–4 polar tubule coils. Myxospores measure 10.2 ± 0.6 (8.8–11.6) μm in length, 8.0 ± 0.7 (5.3–8.8) μm in width and 5.6 ± 0.2 (5.1–6.4) μm in thickness. Caudal appendages are 36.6 ± 3.2 (27.4–42.9) μm long. Total spore length is 47.6 ± 3.2 (41.2–53.2) μm. Polar capsules measure 4.0 ± 0.2 (3.4–4.6) by 2.2 ± 0.1 (1.9–2.6) μm. Small subunit ribosomal RNA-based tree topologies position H. cardii n. sp. within a lineage of marine myxobolids that is mostly comprised of other Henneguya species. Host-relatedness is reinforced as the main evolutionary driver for myxobolids, with the positioning of H. cardii n. sp. further suggesting tissue tropism as another important evolutionary driver for marine heart infecting Henneguya. Nonetheless, the inner complexity of this lineage suggests that identification of the evolutionary patterns driving its phylogeny will require discovery of the true diversity of marine myxobolids.

Small nucleolar RNAs (snoRNAs) are short non-coding RNAs that are abundant in the nucleoli of eukaryotic cells and play a crucial role in various aspects of ribosomal RNA (rRNA) maturation, including modifications such as 2′-O-methylation or pseudouridylation. On the other hand, Giardia duodenalis is a microaerophilic, flagellated, binucleate protozoan responsible for causing giardiasis. Although numerous snoRNAs have been detected in Giardia, their investigation remains limited. Nevertheless, they have been found to play a crucial role in the rRNA precursor processing pathway and influence other cellular functions. In addition, it has been proposed that some microRNAs are generated from these snoRNAs through excision by the Giardia endoribonuclease Dicer. These microRNAs are believed to contribute to the regulation of antigenic variation, which allows the parasite to evade the host immune response. Specifically, they play a role in modulating variant-specific surface proteins (VSPs) and other cysteine-rich surface antigens (CSAs). The main objective of this study was to bring together the available data on snoRNAs in Giardia, uncovering their functions in various processes and their importance on a global scale. In addition, the research delved into potential microRNAs speculated to originate from snoRNAs, exploring their impact on cellular processes.

Sculpins (coastrange and slimy) and sticklebacks (ninespine and threespine) are widely distributed fishes cohabiting 2 south-central Alaskan lakes (Aleknagik and Iliamna), and all these species are parasitized by cryptic diphyllobothriidean cestodes in the genus Schistocephalus. The goal of this investigation was to test for host-specific parasitic relationships between sculpins and sticklebacks based upon morphological traits (segment counts) and sequence variation across the NADH1 gene. A total of 446 plerocercoids was examined. Large, significant differences in mean segment counts were found between cestodes in sculpin (mean = 112; standard deviation [s.d.] = 15) and stickleback (mean = 86; s.d. = 9) hosts within and between lakes. Nucleotide sequence divergence between parasites from sculpin and stickleback hosts was 20.5%, and Bayesian phylogenetic analysis recovered 2 well-supported clades of cestodes reflecting intermediate host family (i.e. sculpin, Cottidae vs stickleback, Gasterosteidae). Our findings point to the presence of a distinct lineage of cryptic Schistocephalus in sculpins from Aleknagik and Iliamna lakes that warrants further investigation to determine appropriate evolutionary and taxonomic recognition.

Equine strongylid parasites are ubiquitous around the world and are main targets of parasite control programmes. In recent years, automated fecal egg counting systems based on image analysis have become available allowing for collection and analysis of large-scale egg count data. This study aimed to evaluate equine strongylid fecal egg count (FEC) data generated with an automated system over three years in the US with specific attention to seasonal and regional trends in egg count magnitude and sampling activity. Five US regions were defined; North East, South East, North Central, South Central and West. The data set included state, region and zip code for each FEC. The number of FECs falling in each of the following categories were recorded: (1) 0 eggs per gram (EPG), (2) 1 ⩽ 200 EPG, (3) 201 ⩽ 500 EPG and (4) >500 EPG. The data included 58 329 FECs. A fixed effects model was constructed fitting the number of samples analysed per month, year and region, and a mixed effects model was constructed to fit the number of FECs falling in each of the 4 egg count categories defined above. The overall proportion of horses responsible for 80% of the total FEC output was 18.1%, and this was consistent across years, months and all regions except West, where the proportion was closer to 12%. Statistical analyses showed significant seasonal trends and regional differences of sampling frequency and FEC category. The data demonstrated that veterinarians tended to follow a biphasic pattern when monitoring strongylid FECs in horses, regardless of location.

Little is known about helminth parasites of the Bismarck Archipelago, in either archaeological or modern contexts. This study presents a parasitological analysis of soil samples from Early Lapita habitation layers at Kamgot (3300–3000 BP). Evidence for the presence of pigs and dogs and the timing of their arrival in Early Lapita contexts have been contested in the literature. The finding of parasite eggs in samples from Kamgot supports the presence of pigs and dogs at the site. Six types of helminth eggs were identified: pig nematode Trichuris suis, dog nematode Toxocara canis, and cestode Dipylidium caninum, as well as two unknown trematodes and a possible anoplocephalid cestode, thereby indicating the local presence of other mammals or birds. This study represents the first confirmed record of ancient helminth parasites in tropical Oceania.